Begin by finely chopping the peeled onion and garlic.
Thoroughly clean all seafood by rinsing under cold running water. Peel shrimp if necessary, and ensure all shells are brushed and rinsed.
Cut the octopus into one-inch pieces and slice the firm white fish into moderately thick pieces.
Heat the stove to medium-high. Add olive oil, onions, and garlic; sauté until transparent (3-5 minutes).
Add octopus, lightly fry, then introduce fish stock, white wine, oregano, and tomato paste. Cover and bring to a boil.
After approximately five minutes, add crab, fish, clams, and mussels.
Cook for an additional five minutes. Turn off the stove and add shrimp or prawns, allowing residual heat to cook them.
Taste, and adjust with salt and pepper as needed.
Serve immediately in earthenware bowls with lime wedges and parsley.